Comparison of exercise electrocardiogram and exercise echocardiography in intermediate-risk chest pain patients

The novel exercise computer-assisted high-frequency QRS analysis (HF/QRS) has demonstrated improved sensitivity and specificity over the conventional ST/electrocardiogram-segment analysis (ST/ECG) in the detection of myocardial ischemia. The aim of the present study was to compare the diagnostic value of the validated exercise echocardiography (ex-Echo) with the novel exercise ECG (ex-ECG) including HF/QRS and ST/ECG analysis.

A prospective cohort study was conducted in the emergency department of a tertiary care teaching Hospital. Patients with chest pain (CP), normal resting ECGs, troponins, and echocardiography, labeled as "intermediate-risk" for adverse coronary events, underwent the novel ex-ECG and ex-Echo. An ST-segment depression of at least 2 mV or at least 1 mV when associated with CP was considered as an index of ischemia, as well as a decrease of at least 50% in HF/QRS intensity, or new wall motion abnormalities on ex-Echo. Exclusion criteria were QRS duration of at least 120 milliseconds, poor echo-acoustic window, and inability to exercise. Patients were followed up to 3 months. The end point was the composite of coronary stenoses of 50% or greater at angiography or acute coronary syndrome, revascularization, and cardiovascular death on the 3-month follow-up.

Of 188 patients enrolled, 18 achieved the end point. The novel ex-ECG and ex-Echo showed comparable negative predictive value (97% vs 96%; P = .930); however, sensitivity was 83% vs 61%, respectively (P = .612), and specificity was 64% vs 92%, respectively,(P = .026). The areas on receiver operating characteristic analysis were comparable (ex-ECG: 0.734 [95% confidence interval, or CI, 0.62-0.85] vs ex-Echo: 0.767 [CI, 0.63-0.91]; C statistic, P = .167). On multivariate analysis, both ex-ECG (hazard ratio, 5; CI, 1-20; P = .017) and ex-Echo (HR, 12; CI, 4-40; P < .001) were predictors of the end point.

In intermediate-risk CP patients, the novel ex-ECG including HF/QRS added to ST/ECG analysis was a valuable diagnostic tool and might be proposed to avoid additional imaging. However, the novel test needs additional study before it can be recommended as a replacement for current techniques.